9-1-1 is a phone number widely recognized in North America as an emergency phone number that is used to contact emergency dispatch personnel. Enhanced 9-1-1 (E9-1-1) is defined by an emergency call being selectively routed to an appropriate Public Service Answering Point (PSAP), based on an identifier, such as an Automatic Number Identifier (ANI), a Pseudo Automatic Number Identifier (pANI), an Emergency Services Routing Key (ESRK), any of which can generically be referred to an ESxK or a locator key. The locator key can include the transmission of callback number and location information when 9-1-1 is used. E9-1-1 may be implemented for wireless (e.g., cellular) landline, or VoIP networks.
A PSAP is a dispatch office that receives 9-1-1 calls (voice or text messages) from the public. A PSAP may be a local, fire or police department, an ambulance service or a regional office covering all services. As used herein, the term PSAP can alternatively refer to an Emergency Call Center (ECC) a term employed for Voice over Internet Protocol (VoIP) systems.